1. Field of the Invention
This invention relates generally to a mechanism that facilitates the use of printed circuit boards with computer systems. More particularly, it relates to an ejector for ejecting a riser card from one or more connectors on a backplane board.
2. Discussion of the Related Art
Computer systems are provided with a processor and related circuitry. These are typically mounted on a backplane board within a computer chassis, sometimes referred to as a “motherboard.” It is desirable in computer systems to enhance the capabilities of the backplane board by adding one or more riser cards, which are provided with electronic components that expand or enhance the capabilities of the backplane board.
Riser cards must be connected to backplane boards both electronically and physically. Numerous methods are used to accomplish this, one being the use of card-edge connectors. A typical card-edge connector is an elongate plastic body with a slot on the top face that runs along the longitudinal axis of the body. This slot is configured to receive a riser card. The inner edges of the slot are provided with a series of flexible contacts that mate with corresponding traces on the riser card as it is inserted into the connector. Each contact of the connector is connected to a pin (usually an integral part of the contact) that extends out the bottom face of the connector body. The pins are configured for insertion into corresponding holes in a backplane board and subsequently are soldered to provide a reliable electrical connection between the connector and the backplane board. Examples of card-edge connector are Tyco PN 650707-1 (101 dual position, PS/2 bus type) and FCI PN CEE2X60PF102PY4 (120 positions).
Another method to connect riser cards to backplane boards is to use header-receptacle combinations as shown in FIG. 1. The typical header 27 comprises a header block 51 that houses a series of pins 33, which extend from opposed sides of the header block. Pin ends 52 extend through an alignment card 58 and are inserted and soldered in corresponding holes 56 in a riser card. The other pin ends 53 are inserted into corresponding holes in a mating receptacle 28. The mating receptacle comprises a receptacle block 54 that house contacts for making electrical and physical connection with the pins of the header. Each contact 56 of the mating receptacle is connected to one end 56 of a pin 55 (usually an integral part of the contact) that extends out the bottom face of the receptacle body. The other end 57 of the pin is configured for insertion into a corresponding hole in a backplane board 26 and subsequently is soldered to provide a reliable electrical connection between the receptacle and the board. An example of a header is a Tyco Minitek® shrouded header PN 98464-G61-50U, while an example of a receptacle is Tyco Minitek® PCB receptacle PN 55510-350TR.
Most if not all methods of connecting a riser card to a backplane board suffer from a common problem. The contacts of the connector used to accomplish the connection between riser card and backplane board firmly grip the traces or pins with which they mate. This is necessary to insure a firm electrical connection between the card and board, as well as to promote physical stability for the card. However, the firm grip of the contacts typically makes it difficult to remove a riser card from a backplane board necessitating high extraction forces. Further, riser cards often have delicate componentry that must be handled manually, a particular problem where the circuitry is so tightly packed on the riser card such that there is little available area for grasping the riser card. This situation is exacerbated by the fact that riser cards are likewise often closely spaced to one another, magnifying the difficulties discussed above.
Various solutions to these problems have been proposed. One involves the inclusion of a built-in ejector in a riser card connector. This method, however, suffers from distinct disadvantages. First, having a built-in ejector adds cost and complexity to a standard connector. Second, many built-in ejector designs are difficult to use and hence do not provide a significant advantage over manually removing the card.
Another proposed solution is to place an ejector along the top edge of the riser card. This provides convenient access to the ejector when multiple cards are installed adjacent to one another. This also provides a lever ejector that only requires rotation in order to remove the riser card. However, this ejector arrangement requires an additional structure to provide a bearing surface for the lever. This structure is often placed on the backplane board and extends upward roughly the height of the riser card, adding cost and complexity. Further, securely attaching the structure to the backplane board to provide a stable bearing surface is difficult, and top-edge ejectors typically are relatively small and provide a limited mechanical advantage for disengaging a riser card.
Yet another card ejector, indicated generally at 10 in FIG. 1, uses a lever attached to the side of a riser card 24, which is positioned above backplane board 26. The lever 12 of the prior art ejector comprises an upper manipulation region 14, a lower abutting region 36, which presents a curved engagement tip 34 and an attachment means 22 for pivotably mounting the lever 12 to a side of the riser card 24. The lever is attached in such a position that the lower abutting region 36 extends beyond the lower edge of the riser card during pivoting of the lever. The riser-card ejector 10 is configured with a recess 29 along its upper edge to accept a pulling force to rotate the lever 12 about the attachment means 22 from an abutting position with riser card 24 (lever 12 in dotted lines) to an abutting position with a backplane board 26, unseating the header 27 of the attached riser card 24 from the mating receptacle 28 of the backplane board 26. This card ejector is problematic, however, when there is no sheet metal or other off-board interface against which the lower abutting region can press as ejection is accomplished. Backplane boards are often tightly packed with components, leaving no room for the lever to abut the board during ejection. If a board is designed to take the abutment region into account, fewer components may be placed on the backplane board.